[WIP]modify avatar editor

[kaizumaki]

close #21

I get a CORS error when opening the avatar edit window. (And it is sometimes error free.)
I think the cause of this is in the CORS header setting in amplify. What do you think?

[loleg]

Just two add a small thought here: it looks like your code changes update the editor, but not directly address the CORS problem - right? CORS errors are usually an issue with the server configuration - in this case, the S3 site hosting your image does not like to get requests from localhost. You might want to test this again on a remote server with a real domain name, like a stage server. And if I am correct, then provide instructions for developers about a workaround - like using another S3 provider or some other storage mechanism in testing.